Magnetic plasmonic nanoparticle dimer

ABSTRACT

Described embodiments include a system, method, and apparatus. The apparatus includes a plasmonic nanoparticle dimer. The dimer includes a first plasmonic nanoparticle having a first magnetic element covered by a first negative-permittivity layer comprising a first plasmonic outer surface. The dimer includes a second plasmonic nanoparticle having a second magnetic element covered by a second negative-permittivity layer comprising a second plasmonic outer surface. The dimer includes a separation control structure configured to establish a dielectric-filled gap between the first plasmonic outer surface and the second plasmonic outer surface. A magnetic attraction between the first magnetic element and the second magnetic element binds the first plasmonic nanoparticle and the second plasmonic nanoparticle together, separated by the dielectric-filled gap established by the separation control structure. The first plasmonic outer surface, the dielectric-filled gap, and the second plasmonic outer surface are configured to cooperatively support one or more mutually coupled plasmonic excitations.

If an Application Data Sheet (ADS) has been filed on the filing date ofthis application, it is incorporated by reference herein. Anyapplications claimed on the ADS for priority under 35 U.S.C. §§119, 120,121, or 365(c), and any and all parent, grandparent, great-grandparent,etc. applications of such applications, are also incorporated byreference, including any priority claims made in those applications andany material incorporated by reference, to the extent such subjectmatter is not inconsistent herewith.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the earliest availableeffective filing date(s) from the following listed application(s) (the“Priority Applications”), if any, listed below (e.g., claims earliestavailable priority dates for other than provisional patent applicationsor claims benefits under 35 USC §119(e) for provisional patentapplications, for any and all parent, grandparent, great-grandparent,etc. applications of the Priority Application(s)).

PRIORITY APPLICATIONS

None.

If the listings of applications provided above are inconsistent with thelistings provided via an ADS, it is the intent of the Applicant to claimpriority to each application that appears in the DomesticBenefit/National Stage Information section of the ADS and to eachapplication that appears in the Priority Applications section of thisapplication.

All subject matter of the Priority Applications and of any and allapplications related to the Priority Applications by priority claims(directly or indirectly), including any priority claims made and subjectmatter incorporated by reference therein as of the filing date of theinstant application, is incorporated herein by reference to the extentsuch subject matter is not inconsistent herewith.

SUMMARY

For example, and without limitation, an embodiment of the subject matterdescribed herein includes an apparatus. The apparatus includes aplasmonic nanoparticle dimer. The plasmonic nanoparticle dimer includesa first plasmonic nanoparticle having a first magnetic element at leastpartially covered by a first negative-permittivity layer comprising afirst plasmonic outer surface. The plasmonic nanoparticle dimer includesa second plasmonic nanoparticle having a second magnetic element atleast partially covered by a second negative-permittivity layercomprising a second plasmonic outer surface. The plasmonic nanoparticledimer includes a separation control structure configured to establish adielectric-filled gap between the first plasmonic outer surface and thesecond plasmonic outer surface. A magnetic attraction between the firstmagnetic element and the second magnetic element binds the firstplasmonic nanoparticle and the second plasmonic nanoparticle together,separated by the dielectric-filled gap established by the separationcontrol structure. The first plasmonic outer surface, thedielectric-filled gap, and the second plasmonic outer surface areconfigured to cooperatively support one or more mutually coupledplasmonic excitations.

In an embodiment, the apparatus includes the plasmonic nanoparticledimer in a gas, fluid, or solid colloid. In an embodiment, the apparatusincludes the plasmonic nanoparticle dimer in a gas, fluid, or solidcolloidal. In an embodiment, the apparatus includes the plasmonicnanoparticle dimer in a colloidal suspension. In an embodiment, theapparatus includes the plasmonic nanoparticle dimer in a colloidalsolution. In an embodiment, the plasmonic nanoparticle dimer includes aplasmonic nanoparticle trimer. The trimer includes a third plasmonicnanoparticle having a third magnetic element at least partially coveredby a third negative-permittivity layer comprising a third plasmonicouter surface.

For example, and without limitation, an embodiment of the subject matterdescribed herein includes a system. The system includes a mixture of aplurality of plasmonic nanoparticle dimers in a dispersion medium. Eachplasmonic nanoparticle dimer of the plurality of plasmonic nanoparticledimers includes a first plasmonic nanoparticle having a first magneticelement at least partially covered by a first negative-permittivitylayer comprising a first plasmonic outer surface. Each plasmonicnanoparticle dimer of the plurality of plasmonic nanoparticle dimersincludes a second plasmonic nanoparticle having a second magneticelement at least partially covered by a second negative-permittivitylayer comprising a second plasmonic outer surface. The system includesthe dispersion medium. Each plasmonic nanoparticle dimer of theplurality of plasmonic nanoparticle dimers includes a separation controlstructure configured to establish a dielectric-filled gap between thefirst plasmonic outer surface and the second plasmonic outer surface. Amagnetic attraction between the first magnetic element and the secondmagnetic element binds the first plasmonic nanoparticle and the secondplasmonic nanoparticle together, separated by the dielectric-filled gapestablished by the separation control structure. The first plasmonicouter surface, the dielectric-filled gap, and the second plasmonic outersurface are configured to cooperatively support one or more mutuallycoupled plasmonic excitations. In an embodiment, the system includes acapsule configured to hold the mixture.

For example, and without limitation, an embodiment of the subject matterdescribed herein includes a method. The method includes applying a layerof dielectric material to at least a portion of a first plasmonic outersurface of each plasmonic nanoparticle of a plurality of first plasmonicnanoparticles. Each plasmonic nanoparticle of the plurality of firstplasmonic nanoparticles having a first magnetic element at leastpartially covered by a first negative-permittivity layer comprising afirst plasmonic outer surface. The method includes placing a pluralityof second plasmonic nanoparticles proximate to the plurality of firstplasmonic nanoparticles. Each plasmonic nanoparticle of the plurality ofsecond plasmonic nanoparticles having a second magnetic element at leastpartially covered by a second negative-permittivity layer comprising asecond plasmonic outer surface. The method includes forming a pluralityof plasmonic nanoparticle dimers. Each plasmonic nanoparticle dimer ofthe plurality of plasmonic nanoparticle dimers respectively comprising aplasmonic nanoparticle of the plurality of first plasmonic nanoparticlesmagnetically bound to a plasmonic nanoparticle of the plurality ofsecond plasmonic nanoparticles. A dielectric-filled gap is establishedby the applied layer of dielectric material between the first plasmonicouter surface of the first bound plasmonic nanoparticle and the secondplasmonic outer surface of the second bound plasmonic nanoparticle.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example embodiment of an apparatus 100;

FIG. 2 illustrates an example embodiment of an apparatus 200;

FIG. 3 illustrates an example operational flow 300;

FIG. 4A is a schematic side view of an example apparatus 401;

FIG. 4B is an exploded view of the example apparatus 401;

FIG. 5 illustrates an example system 500; and

FIG. 6 illustrates an example operational flow 600.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here.

FIG. 1 illustrates an example embodiment of an apparatus 100. Theapparatus includes a magnetic substrate 110 at least partially coveredby a first negative-permittivity layer 114 comprising a first plasmonicouter surface 112. The magnetic field of the magnetic substrate isillustrated by a magnetic field 116. The apparatus includes a plasmonicnanoparticle 120 having a magnetic element 122 at least partiallycovered by second negative-permittivity layer 128 comprising a secondplasmonic outer surface 124. The magnetic field of the magnetic elementis illustrated by a magnetic field 126. An example magnetic plasmonicnanoparticle with continuous Au shell layers is described by C. S. Levinet al., Magnetic—Plasmonic Core—Shell Nanoparticles, ACS Nano, 2009, 3(6), pp 1379-1388, 2009) (accessed Aug. 3, 2015, athttp://pubs.acs.org/doi/abs/10.1021/nn900118a). An example process offabricating magnetic nanoparticles is described in K. Lee, MagneticNanoparticle Formation, U.S. Pat. No. 8,247,025.

The apparatus 100 includes a dielectric-filled gap 140 between the firstplasmonic outer surface 112 and the second plasmonic outer surface 124.The first plasmonic outer surface, the dielectric-filled gap, and thesecond plasmonic outer surface are configured to support one or moremutually coupled plasmonic excitations. In an embodiment, use of theword “plasmonic” such as in “plasmonic outer surface” or “plasmonicnanoparticle” includes a structure or configuration supporting aplasmonic excitation either alone or in combination with at least oneother element.

In an embodiment, the magnetic substrate 100 includes magnetisablesubstrate. In an embodiment, the magnetic substrate includes a magneticsubstrate configured to temporarily magnetically attract the plasmonicnanoparticle 120. In an embodiment, the magnetisable substrate, thefirst plasmonic nanoparticle outer surface 124 or the dielectric of thedielectric-filled gap 140 include an adhesive configured to bond theplasmonic nanoparticle and the magnetic substrate after the temporarymagnetization is turned off. In an embodiment, the magnetic substrateincludes a magnetic substrate configured to permanently magneticallyattract the plasmonic nanoparticle. In an embodiment, the magneticsubstrate 110, the second plasmonic outer surface 124, or the dielectricof the dielectric-filled gap 140 include an adhesive configured to bondthe plasmonic nanoparticle and the magnetic substrate.

In an embodiment, the magnetic substrate 110 includes a plurality ofmagnetized landing or retention areas each configured to magneticallyattract a respective plasmonic nanoparticle of a plurality of plasmonicnanoparticles. In an embodiment, the plurality magnetized landing orretention areas are each configured to retain one plasmonicnanoparticle. In an embodiment, the plurality magnetized landing orretention areas are each configured to retain one plasmonic nanorod. Inan embodiment, the magnetic substrate includes a plurality of magnetizedpixelated landing or retention areas. In an embodiment, the plurality ofmagnetized landing or retention areas are spatial separated from eachother. In an embodiment, the magnetic substrate includes a magneticsubstrate having a switchable magnetic state. For example, a switchablemagnetic state may include a magnetic state switchable on and off. Forexample, a switchable magnetic state may include a magnetic stateswitchable between a first magnetic field strength and a second magneticstrength. In an embodiment, the first plasmonic outer surface or thesecond plasmonic outer surface includes an adhesive configured to bondthe plasmonic nanoparticle 120 and the magnetic substrate 110. In anembodiment, the adhesive is a dielectric adhesive that at leastpartially forms the dielectric-filled gap 140. In an embodiment, thefirst negative-permittivity layer has negative permittivity within adefined frequency range. In an embodiment, the secondnegative-permittivity layer has negative permittivity within a definedfrequency range.

In an embodiment, the first negative-permittivity layer 114 includes ametallic layer. In an embodiment, the first negative-permittivity layerincludes a semi-metallic layer. In an embodiment, the firstnegative-permittivity layer includes a semiconductor layer. In anembodiment, the first negative-permittivity layer includes a polaritonicdielectric layer. In an embodiment, the plasmonic outer surface 124 iscovered with the second negative-permittivity layer.

In an embodiment, the plasmonic nanoparticle 120 includes a plasmonicnanocube particle. In an embodiment, the plasmonic nanocube particle hasa side length between about 50 nm and about 350 nm. In an embodiment,the plasmonic nanoparticle includes a plasmonic nanorod. In anembodiment, the plasmonic nanoparticle includes a decahedra, cage,spheroid, or triangular nanoprism shaped plasmonic nanoparticle. In anembodiment, the plasmonic nanoparticle has a size ranging between 1-100nm. In an embodiment, the plasmonic nanoparticle has a size rangingbetween 20 and 400 nm. In an embodiment, the plasmonic nanoparticleincludes a plasmonic nanoparticle having an arbitrary shape. Forexample, an arbitrary shape may include a sphere, bow tie, or some otherarbitrary shape functioning as a magnetic plasmonic nanoparticle. In anembodiment, the plasmonic nanoparticle includes a first plasmonicnanoparticle and a second plasmonic nanoparticle. The first plasmonicnanoparticle comprising a first magnetic element having a first magneticstrength. The second plasmonic nanoparticle comprising a second magneticelement having a second magnetic strength different from the firstmagnetic strength. For example, nanocubes with different strengths orlayouts of their magnetic elements are expected to allow asequence-based self-assembly on the magnetic substrate. In anembodiment, the plasmonic nanoparticle includes a first plasmonicnanoparticle and a second plasmonic nanoparticle. The first plasmonicnanoparticle comprising a first side characteristic or shape dimensions.The second plasmonic nanoparticle comprising a second sidecharacteristic or shape dimensions that are different from the firstside characteristic or shape dimensions.

In an embodiment, the magnetic element 122 includes a magnetic core. Inan embodiment, the magnetic element includes a ferromagnetic orparamagnetic element. In an embodiment, the magnetic element includes apermanent magnetic element. In an embodiment, the permanent magneticelement includes a dipole, quadrapole, or more general field geometry.In an embodiment, the magnetic element includes a magnetisable element.In an embodiment, the magnetic element includes a magnetic elementconfigured to temporarily magnetically attract the magnetic substrate.In an embodiment, the magnetic element includes a magnetic elementconfigured to permanently magnetically attract the magnetic substrate.

In an embodiment, the second negative-permittivity layer 128 includes anoble metal. In an embodiment, the second negative-permittivity layer atleast partially encloses the magnetic element. In an embodiment, thesecond negative-permittivity layer is formed over at least a side of themagnetic element. In an embodiment, the second negative-permittivitylayer is covered by a dielectric coating or film configured to at leastpartially form the dielectric-filled gap. In an embodiment, the firstplasmonic outer surface 124 is at least partially cladded with thesecond negative-permittivity layer. In an embodiment, the secondnegative-permittivity layer includes a metallic layer. In an embodiment,the second negative-permittivity layer includes a semi-metallic layer.In an embodiment, the second negative-permittivity layer includes asemiconductor layer or a polaritonic dielectric layer. In an embodiment,the first plasmonic outer surface 124 or the second plasmonic outersurface includes an adhesive configured to bond the plasmonicnanoparticle and the magnetic substrate. In an embodiment, the adhesiveis a dielectric adhesive that at least partially forms thedielectric-filled gap 140.

In an embodiment, the at least a portion of the dielectric-filled gap140 comprises a dielectric coating or layer applied to the firstplasmonic outer surface 112 of the magnetic substrate 110. In anembodiment, the at least a portion of the dielectric-filled gapcomprises a dielectric coating or layer applied to the second plasmonicouter surface 124 of the plasmonic nanoparticle 120. In an embodiment,the dielectric-filled gap has a gap spacing of less than 200 nm. In anembodiment, the dielectric-filled gap has a gap spacing of less than 100nm. In an embodiment, the dielectric-filled gap has a gap spacing ofless than 50 nm. In an embodiment, the dielectric-filled gap has a gapspacing of less than 25 nm. In an embodiment, the dielectric-filled gaphas a gap spacing greater than 0 nm and less than 50 nm. In anembodiment, the dielectric-filled gap has a gap spacing of greater than5 nm. In an embodiment, the dielectric-filled gap has a gap spacing ofgreater than 2 nm. In an embodiment, the dielectric includes a hard orsoft dielectric material.

In an embodiment, the magnetic field 116 of the magnetic substrate 110and the magnetic field 126 of the magnetic element 122 of the plasmonicnanoparticle 120 are configured to magnetically interact. In anembodiment, the magnetic interaction includes a magnetic attraction ofthe plasmonic nanoparticle toward a preselected location on the firstplasmonic outer surface. In an embodiment, the magnetic interactionincludes a magnetic repulsion of the plasmonic nanoparticle away from apreselected location on the first plasmonic outer surface. In anembodiment, the magnetic interaction between the magnetic substrate andthe magnetic element of the plasmonic nanoparticle controls the gapdimension of the dielectric-filled gap. In an embodiment, a compliantdielectric material forms at least a portion of the dielectric-filledgap and controls the gap dimension between the magnetic substrate andthe magnetic element. In an embodiment, the magnetic interactionincludes an attraction or a repulsion.

In an embodiment of the apparatus 100, the plasmonic nanoparticle 120includes a two plasmonic nanoparticles deposited of the magneticsubstrate 110 in a dimer configuration. In an embodiment, the twoplasmonic nanoparticles are separated by a dielectric coating carried byone or both nanoparticles.

FIG. 2 illustrates an example embodiment of an apparatus 200. Theapparatus includes a magnetic substrate 210 at least partially coveredby a first negative-permittivity layer 214 comprising a first plasmonicouter surface 212. The magnetic field of the magnetic substrate isillustrated by a magnetic field 216. The apparatus includes a pluralityof plasmonic nanoparticles 220, illustrated by plasmonic nanoparticles220A, 220B, and 220C. Plasmonic nanoparticle 220A is illustrative ofeach plasmonic nanoparticle of the plurality of plasmonic nanoparticles.Plasmonic nanoparticle 220A comprises a magnetic element 222A at leastpartially covered by a second negative-permittivity layer 228Acomprising a second plasmonic outer surface 224A. The magnetic field ofthe magnetic core is illustrated by a magnetic field 226A. The apparatusincludes a respective dielectric-filled gap 240 between the firstplasmonic outer surface 212 and the second plasmonic outer surface 224Aof each plasmonic nanoparticle of the plurality of plasmonicnanoparticles, illustrated by the second negative-permittivity layer228A of plasmonic nanoparticle 220A. The first plasmonic outer surface212, the dielectric-filled gap 240, and the second plasmonic outersurface (illustrated by the second plasmonic outer surface 224A ofplasmonic nanoparticle 220A) are configured to support one or moremutually coupled plasmonic excitations.

In an embodiment, the plurality of plasmonic nanoparticles 220 areindividually deposited in a controlled manner on the first plasmonicouter surface 212 of the magnetic substrate 210. In an embodiment,individually deposited plasmonic nanoparticles include plasmonicnanotubes individually positioned or individually placed on the firstplasmonic outer surface of the magnetic substrate. In an embodiment,individually deposited plasmonic nanoparticles include plasmonicnanoparticles individually positioned or placed on the first plasmonicouter surface of the magnetic substrate. For example, in an embodiment,the plurality of plasmonic nanoparticles are individually deposited in acontrolled manner on the first plasmonic outer surface of the magneticsubstrate using a two-dimensional printer or a three-dimensionalprinter. In an embodiment, the plurality of plasmonic nanoparticles areindividually deposited in a controlled manner on the first plasmonicouter surface of the magnetic substrate using a magnetic interactionbetween the magnetic field 216 of the magnetic substrate and therespective magnetic elements 222A of the plurality of plasmonicnanoparticles 220. In an embodiment, each plasmonic nanoparticle of theplurality of plasmonic nanoparticles is individually deposited in acontrolled manner on the first plasmonic outer surface of the magneticsubstrate in a pattern storing data. This may be a magnetic memory(i.e., individual pixels may be magnetized/demagnetized) with randomaccess, or serial access, or just a magnetic layer that may be writtenon, for example like a disk-type magnetic head. In an embodiment, smallscale magnetic fields are used to maneuver an individual nanoparticle toa preselected position functioning as a memory bit. In an embodiment,the plurality of individually deposited magnetic plasmonic nanoparticlesare respectively individually deposited with respect to each other onthe first plasmonic outer surface of the magnetic substrate. In anembodiment, the plurality of individually deposited magnetic plasmonicnanoparticles are respectively individually positioned on the firstplasmonic outer surface of the magnetic substrate. In an embodiment, theplurality of individually deposited magnetic plasmonic nanoparticles arerespectively individually deposited with respect to a magnetized landingor retention area on the first plasmonic outer surface. For example, themagnetized landing or retention area may be configured to placenanocubes. In an embodiment, the magnetized landing or retention areaincludes a magnetized landing pixel or a retention pixel. The magneticpixels may be static or dynamically changeable so as to automaticallyreposition nanocubes. In an embodiment, the plurality of individuallydeposited magnetic plasmonic nanoparticles are respectively retained intheir respective positions on the first plasmonic outer surface by amagnetic attraction between the magnetic substrate and the respectivemagnetic element of each individually deposited plasmonic nanoparticle.For example, the positioning may be relative to other nanocubes. Forexample, the plurality of plasmonic magnetic nanocubes may constitute aself-assembling array on the first plasmonic outer surface.

In an embodiment, the plurality of individually deposited plasmonicnanoparticles 220 are temporarily retained in their respective positionson the first plasmonic outer surface 212 of the magnetic substrate 210by a magnetic attraction between the magnetic substrate and therespective magnetic element of each individually deposited plasmonicnanoparticle. For example, the temporary retention may be implemented bymagnetizing the magnetic substrate or magnetizing the magnetic elementof a plasmonic nanoparticle of the plurality of plasmonic nanoparticles.The magnetizing may be implemented by passing an electric currentthrough a coil. In an embodiment, the magnetisable substrate 210, thefirst plasmonic outer surface, the second plasmonic outer surface 224A,or the dielectric of the dielectric-filled gap 240 include an adhesiveconfigured to bond the plasmonic nanoparticle and the magnetic substrateafter the magnetization is turned off

In an embodiment, the plurality of individually deposited plasmonicnanoparticles 220 are temporarily retained in their respective positionson the magnetic substrate 210 by a magnetization of the magneticsubstrate. In an embodiment, the magnetization is induced by an electriccurrent. In an embodiment, the plurality of individually depositedplasmonic nanoparticles are respectively permanently retained in theirrespective positions on the magnetic substrate by a magnetic attractionbetween the magnetic substrate and the respective magnetic element ofeach individually deposited plasmonic nanoparticle. In an embodiment,the plurality of plasmonic nanoparticles are each respectively depositedin a preselected location on the substrate in a configurationimplementing a photonic circuit. In an embodiment, the plurality ofplasmonic nanoparticles are each respectively deposited in a preselectedlocation on the substrate in a configuration implementing a visualdisplay.

In an embodiment, the first negative-permittivity layer 214A includes ametallic layer. In an embodiment, the second negative-permittivity layer228A includes a metallic layer. In an embodiment, the magnetic substrate210 and the magnetic element 222A of each nanoparticle of the pluralityof nanoparticles 220 are configured to magnetically interact. In anembodiment, the first plasmonic outer surface 212 of the magneticsubstrate is covered with the first negative-permittivity layer. In anembodiment, the second plasmonic outer surface 224A is covered with thesecond negative-permittivity layer. In an embodiment, the firstnegative-permittivity layer 214 has negative permittivity within adefined frequency range. In an embodiment, the secondnegative-permittivity layer has negative permittivity within a definedfrequency range.

In an embodiment of the apparatus 200, the plurality of plasmonicnanoparticles 220 were collectively delivered to the first plasmonicouter surface 212 of the magnetic substrate 210, and individuallypositioned or placed by a magnetic field on the first plasmonic outersurface of the magnetic substrate in a selected arrangement. In anembodiment, the plurality of plasmonic nanoparticles are each depositedin a respective preselected location on the first plasmonic outersurface of the substrate in a configuration storing selected data. In anembodiment, the plurality of plasmonic nanoparticles are eachrespectively deposited in a preselected location on the first plasmonicouter surface in a configuration implementing a photonic circuit. In anembodiment, the plurality of plasmonic nanoparticles are eachrespectively deposited in a preselected location on the first plasmonicouter surface in a configuration implementing a visual display.

In an embodiment of the apparatus 200, the first negative-permittivitylayer 214 includes a metallic layer. In an embodiment the secondnegative-permittivity layer 228A includes a metallic layer.

FIG. 3 illustrates an example operational flow 300. After a startoperation, the operational flow includes a reception operation 310. Thereception operation includes electronically receiving data indicative ofa selected pattern to be formed by a plurality of plasmonicnanoparticles deposited on a magnetic substrate configured tomagnetically attract magnetic plasmonic nanoparticles. The magneticsubstrate at least partially covered by a first negative-permittivitylayer comprising a first plasmonic outer surface. Each plasmonicnanoparticle of the plurality of plasmonic nanoparticles having arespective magnetic element at least partially covered by a secondnegative-permittivity layer comprising a second plasmonic outer surface.In an embodiment, the magnetic substrate is configured to retain andbond to the magnetic plasmonic nanoparticles. A layout operation 320includes determining a target location of each plasmonic nanoparticle ofthe plurality of plasmonic nanoparticles on the first plasmonic outersurface of the magnetic substrate in conformance with the selectedpattern. An encoding operation 330 includes depositing each of theplurality of plasmonic nanoparticles in a respective determined targetlocation on the first plasmonic outer surface of the magnetic substrate.The operational flow includes an end operation.

In an embodiment, the encoding operation 330 includes individuallydepositing each of the plurality of plasmonic nanoparticles in arespective determined target location on the first plasmonic outersurface of the magnetic substrate. In an embodiment, the encodingoperation includes collectively delivering the plurality of plasmonicnanoparticles proximate to the magnetic substrate and then individuallypositioning each respective plasmonic nanoparticle in a respectivedetermined target location on the first plasmonic outer surface of themagnetic substrate. For example, the plurality of plasmonicnanoparticles may be delivered proximate to the magnetic substratesuspended in a fluid.

FIGS. 4A and 4B illustrate an example apparatus 401. FIG. 4A is aschematic side view of the apparatus and FIG. 4B is an explodedschematic view of the apparatus. The apparatus includes a plasmonicnanoparticle dimer 405. In an embodiment, the nanoparticle dimerincludes intercoupled nanoparticles. The nanoparticle dimer includes afirst plasmonic nanoparticle 420.1 having a first magnetic element 422.1at least partially covered by a first negative-permittivity layer 428.1compromising a first plasmonic outer surface 424.1. The first magneticelement generates a first magnetic field 426.1. The nanoparticle dimerincludes a second plasmonic nanoparticle 420.2 having a second magneticelement 422.2 at least partially covered by a secondnegative-permittivity layer 428.2 comprising a second plasmonic outersurface 424.2. The second magnetic element generates a second magneticfield 426.2. The nanoparticle dimer includes a separation controlstructure 440 configured to establish a dielectric-filled gap 442between the first plasmonic outer surface and the second plasmonic outersurface. In an embodiment, the dielectric-filled gap includes aninter-particle dielectric-filled gap. The magnetic attraction betweenthe first magnetic field of the first magnetic element and the secondmagnetic field of the second magnetic element binds the first plasmonicnanoparticle and the second plasmonic nanoparticle together, separatedby the dielectric-filled gap established by the separation controlstructure. The first plasmonic outer surface, the dielectric-filled gap,and the second plasmonic outer surface are configured to cooperativelysupport one or more mutually coupled plasmonic excitations. A mutuallycoupled plasmonic excitation includes a bonding dimer plasmon mode. Amutually coupled plasmonic excitation includes a bonding surfaceplasmon.

FIG. 4A illustrates an embodiment of the second plasmonic outer surface424.2 completely covered by a second negative-permittivity layer,illustrated by the portion at least partially covered by the secondnegative-permittivity layer 428.2 and remaining portion covered by thesecond negative-permittivity layer 428.2.1.

In an embodiment, the first negative-permittivity layer 428.1 includes ametallic layer. In an embodiment, the second negative-permittivity layer428.2 includes a metallic layer. In an embodiment, the first magneticelement 422.1 includes a ferromagnetic or paramagnetic element. In anembodiment, the first magnetic element 422.1 includes a permanentmagnetic element. In an embodiment, the permanent magnet may include adipole, a quadrapole, or a more general field geometry. In anembodiment, the first magnetic element includes a magnetisable element.

In an embodiment, the separation control structure 440 includes anon-electrically conductive separation control structure. In anembodiment, the separation control structure includes a dielectric filmor dielectric coating applied to the first plasmonic nanoparticle 420.1.In an embodiment, the separation control structure includes at least twodielectric elements projecting outward from the first plasmonic outersurface 424.1. In an embodiment, the separation control structureincludes a dielectric spacer element coupled with the first plasmonicouter surface. In an embodiment, the separation control structureincludes a dielectric-filled gap 442 between the first plasmonic outersurface 424.1 and the second plasmonic outer surface 424.2. In anembodiment, the separation control structure is configured to establishor maintain a selected dielectric-filled gap between the first plasmonicouter surface 424.1 and the second plasmonic outer surface 424.2. In anembodiment, the separation control structure is configured to define adielectric-filled gap between the first plasmonic outer surface and thesecond plasmonic outer surface. In an embodiment, the separation controlstructure is configured to establish a minimum separationdielectric-filled gap between the first plasmonic nanoparticle and thesecond plasmonic nanoparticle. In an embodiment, the dielectric-filledgap is less than a maximum chord length of the first nanoparticle. In anembodiment, the dielectric-filled gap is less than a maximum axis lengthof the first nanoparticle. In an embodiment, the dielectric-filled gapis less than a maximum characteristic length of the first nanoparticle.In an embodiment, the dielectric-filled gap is less than about 10percent of the maximum chord length of the first nanoparticle. In anembodiment, the dielectric-filled gap is greater than about 0.05 percentof the maximum chord length of the first nanoparticle. In an embodiment,the dielectric-filled gap is less than about 50 nm. In an embodiment,the dielectric-filled gap is less than about 20 nm. In an embodiment,the dielectric-filled gap is less than about 10 nm. In an embodiment,the dielectric-filled gap is less than about 5 nm.

In an embodiment, the apparatus 401 includes the nanoparticle dimer 405carried a gas, fluid, or solid colloid. In an embodiment, the apparatusincludes the nanoparticle dimer in a gas, fluid, or solid colloidal. Inan embodiment, the apparatus includes the nanoparticle dimer in acolloidal suspension. In an embodiment, the apparatus includes thenanoparticle dimer in a colloidal solution.

In an embodiment, the plasmonic nanoparticle dimer 405 is configured tohave a selected resonant band frequency signature or profile. Forexample, the selected resonant band frequency signature or profileincludes a resonance frequency shift(s). In an embodiment, the plasmonicnanoparticle dimer is configured to have a selected optical absorptionspectrum. In an embodiment, the plasmonic nanoparticle dimer isconfigured to have a selected Raman scattering signature or profile. Inan embodiment, the plasmonic nanoparticle dimer includes a plasmonicnanoparticle trimer. The trimer includes a third plasmonic nanoparticlecomprising a third magnetic element at least partially covered by athird negative-permittivity layer comprising a third plasmonic outersurface.

FIG. 5 illustrates an example system 500. The system includes a mixture505 of a plurality of plasmonic nanoparticle dimers 510 in a dispersionmedium 530. Each plasmonic nanoparticle dimer of the plurality ofplasmonic nanoparticle dimers includes a first plasmonic nanoparticlecomprising a first magnetic element at least partially covered by afirst negative-permittivity layer comprising a first plasmonic outersurface. The first magnetic element generates a first magnetic field.Each nanoparticle dimer of the plurality of nanoparticle dimers alsoincludes a second plasmonic nanoparticle comprising a second magneticelement at least partially covered by a second negative-permittivitylayer comprising a second plasmonic outer surface. The second magneticelement generates a second magnetic field. Each plasmonic nanoparticledimer of the plurality of plasmonic nanoparticle dimers also includes aseparation control structure configured to establish a dielectric-filledgap between the first plasmonic outer surface and the second plasmonicouter surface. In an embodiment, the dielectric-filled gap includes aninter-particle dielectric-filled gap between the first plasmonicnanoparticle and the second plasmonic nanoparticle. A magneticattraction between the first magnetic element and the second magneticelement binds the first plasmonic nanoparticle and the second plasmonicnanoparticle together, separated by the dielectric-filled gapestablished by the separation control structure. The first plasmonicouter surface, the dielectric-filled gap, and the second plasmonic outersurface are configured to cooperatively support one or more mutuallycoupled plasmonic excitations. The system includes the dispersion medium530. In an embodiment, a plasmonic nanoparticle dimer of the pluralityof plasmonic nanoparticle dimers 510 may be implemented using theplasmonic nanoparticle dimer 405 described in conjunction with FIGS. 4Aand 4B.

In an embodiment, the mixture includes a colloid mixture. For example, acolloid is one of the three primary types of mixtures, with the othertwo being a solution and suspension. For example, a colloid is asolution with particles ranging between 1 and 1000 nanometers indiameter. These particles remain evenly distributed throughout thesolution. These are also known as colloidal dispersions because thesubstances remain dispersed and do not settle to the bottom of acontainer. In colloids, one substance is evenly dispersed in another.The substance being dispersed is referred to as being in the dispersedphase, while the substance in which it is dispersed is in the continuousphase.

In an embodiment, the first negative-permittivity layer of the firstplasmonic nanoparticle includes a metallic layer. In an embodiment, thesecond negative-permittivity layer of the second plasmonic nanoparticleincludes a metallic layer. In an embodiment, the first plasmonic outersurface of the first plasmonic nanoparticle is covered with the firstnegative-permittivity layer. In an embodiment, the second plasmonicouter surface of the second plasmonic nanoparticle is covered with thesecond negative-permittivity layer.

In an embodiment, the dispersion medium 530 includes a fluid. In anembodiment, the dispersion medium includes a solid. In an embodiment,the dispersion medium includes a gas.

In an embodiment, the system 500 includes a capsule 520 configured tohold the mixture 505. In an embodiment, the capsule is configured tohold the mixture during injection, transport, or storage. In anembodiment, the capsule includes a biocompatible capsule. For example, abiocompatible capsule is compatible with living cells, tissues, organs,or systems. For example, a biocompatible capsule poses minimal or norisk of injury, toxicity, or rejection by an immune system of an animal.In an embodiment, the capsule is configured to bind with a biocompatibleligand. In an embodiment, the biocompatible ligand is also configured tobind with a human receptor.

FIG. 6 illustrates an example operational flow 600. After a startoperation, the operational flow includes a coating operation 610. Thecoating operation includes applying a layer of dielectric material to atleast a portion of a first plasmonic outer surface of each plasmonicnanoparticle of a plurality of first plasmonic nanoparticles. Eachplasmonic nanoparticle of the plurality of first plasmonic nanoparticleshaving a first magnetic element at least partially covered by a firstnegative-permittivity layer comprising a first plasmonic outer surface.For example, the coating operation may be implemented by applyingdielectric material to the first plasmonic outer surface 424.1 of thefirst plasmonic nanoparticle 420.1 as described in conjunction withFIGS. 4A and 4B. A positioning operation 620 includes placing aplurality of second plasmonic nanoparticles proximate to the pluralityof first plasmonic nanoparticles. Each plasmonic nanoparticle of theplurality of second plasmonic nanoparticles having a second magneticelement at least partially covered by a second negative-permittivitylayer comprising a second plasmonic outer surface. For example, thepositioning operation may be implemented by placing the second plasmonicnanoparticle 420.2 proximate to the first plasmonic nanoparticle 420.1coated with the dielectric material 440 as described in conjunction withFIGS. 4A and 4B. An assembly operation 630 includes forming a pluralityof plasmonic nanoparticle dimers. Each plasmonic nanoparticle dimer ofthe plurality of plasmonic nanoparticle dimers respectively comprising aplasmonic nanoparticle of the plurality of first plasmonic nanoparticlesmagnetically bound to a plasmonic nanoparticle of the plurality ofsecond plasmonic nanoparticles, with a dielectric-filled gap establishedby the applied layer of dielectric material between the first plasmonicouter surface of the first bound plasmonic nanoparticle and the secondplasmonic outer surface of the second bound plasmonic nanoparticle. Forexample, the assembly operation may be implemented by a magneticattraction between the first magnetic field 426.1 of the first magneticelement 422.1 of the first plasmonic nanoparticle 420.1 and the secondmagnetic field 426.2 of the second magnetic element 422.2 of the secondplasmonic nanoparticle 420.2 as described in conjunction with FIGS. 4Aand 4B. The operational flow includes an end operation.

In an embodiment, the dielectric material includes a dielectric materialthat is deformed less than five percent in the presence of the magneticbinding of a plasmonic nanoparticle of the first plurality of plasmonicnanoparticles to a plasmonic nanoparticle of the plurality of secondnanoparticles. In an embodiment, the applying a dielectric materialincludes applying a layer of dielectric material having a controlled orspecified thickness.

In an embodiment, the dielectric-filled gap is less than 100 nm. In anembodiment, the dielectric-filled gap is less than 10 nm. In anembodiment, the dielectric-filled gap is less than 5 nm. In anembodiment, the dielectric-filled gap is greater than 2 nm and less than50 nm.

In an embodiment of the coating operation 610, the applying a layer ofdielectric material includes adhering a layer of dielectric material tothe plasmonic outer surface of each plasmonic nanoparticle of aplurality of first plasmonic nanoparticles. In an embodiment, theapplying further includes applying a layer of adhesive to the applieddielectric material.

In an embodiment of the positioning operation 620, the placing includesplacing a plurality of second plasmonic nanoparticles proximate to thedielectric layer applied to the plasmonic outer surface of eachplasmonic nanoparticle of the plurality of first plasmonicnanoparticles.

In an embodiment of the assembly operation 630, the forming includesactively facilitating forming a plurality of plasmonic nanoparticledimers. For example, actively facilitating may include a shaking,heating, or cooling of the plurality of first plasmonic nanoparticles orthe plurality of second plasmonic nanoparticles. For example, activelyfacilitating may include adding a catalyst to the plurality of firstplasmonic nanoparticles and the plurality of second plasmonicnanoparticles. For example, actively facilitating may include adding anagent promoting the forming the plurality of plasmonic nanoparticledimers. For example, actively facilitating may include placing theplurality of first plasmonic nanoparticles and the plurality of secondplasmonic nanoparticles in a medium, such as a dispersion medium,allowing or facilitating a mobility of these nanoparticles toward eachother in response to a magnetic attraction between the first magneticelement of the plasmonic nanoparticles of the first plurality ofplasmonic nanoparticles and the second magnetic element of the plasmonicnanoparticles of the second plurality of plasmonic nanoparticles. In anembodiment, the forming includes passively facilitating forming theplurality of plasmonic nanoparticle dimers. For example, passivelyfacilitating may include waiting a length of time for the formation ofthe plurality of plasmonic nanoparticle dimers. In an embodiment, theforming includes forming a plurality of self-assembled plasmonicnanoparticle dimers. In an embodiment, each plasmonic nanoparticle dimerof the plurality of plasmonic nanoparticle dimers respectivelycomprising a plasmonic nanoparticle of the first plurality of plasmonicnanoparticles magnetically bound to a plasmonic nanoparticle of theplurality of second nanoparticles by a magnetic attraction between thefirst magnetic element of the plasmonic nanoparticle of the firstplurality of plasmonic nanoparticles and the second magnetic element ofthe plasmonic nanoparticle of the second plurality of plasmonicnanoparticles.

In an embodiment, the operational flow 600 further includes applying alayer of dielectric material to at least a portion of the secondplasmonic outer surface of each plasmonic nanoparticle of the pluralityof second plasmonic nanoparticles. In an embodiment, thedielectric-filled gap includes a dielectric-filled gap established bythe layer of dielectric material applied to the first plasmonic outersurface of a plasmonic nanoparticle of the plurality of first plasmonicnanoparticles and by the second layer of dielectric material applied tothe second plasmonic outer surface of a plasmonic nanoparticle of theplurality of second plasmonic nanoparticles.

All references cited herein are hereby incorporated by reference intheir entirety or to the extent their subject matter is not otherwiseinconsistent herewith.

In some embodiments, “configured” includes at least one of designed, setup, shaped, implemented, constructed, or adapted for at least one of aparticular purpose, application, or function.

It will be understood that, in general, terms used herein, andespecially in the appended claims, are generally intended as “open”terms. For example, the term “including” should be interpreted as“including but not limited to.” For example, the term “having” should beinterpreted as “having at least.” For example, the term “has” should beinterpreted as “having at least.” For example, the term “includes”should be interpreted as “includes but is not limited to,” etc. It willbe further understood that if a specific number of an introduced claimrecitation is intended, such an intent will be explicitly recited in theclaim, and in the absence of such recitation no such intent is present.For example, as an aid to understanding, the following appended claimsmay contain usage of introductory phrases such as “at least one” or “oneor more” to introduce claim recitations. However, the use of suchphrases should not be construed to imply that the introduction of aclaim recitation by the indefinite articles “a” or “an” limits anyparticular claim containing such introduced claim recitation toinventions containing only one such recitation, even when the same claimincludes the introductory phrases “one or more” or “at least one” andindefinite articles such as “a” or “an” (e.g., “a receiver” shouldtypically be interpreted to mean “at least one receiver”); the sameholds true for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, it will be recognized that suchrecitation should typically be interpreted to mean at least the recitednumber (e.g., the bare recitation of “at least two chambers,” or “aplurality of chambers,” without other modifiers, typically means atleast two chambers).

In those instances where a phrase such as “at least one of A, B, and C,”“at least one of A, B, or C,” or “an [item] selected from the groupconsisting of A, B, and C,” is used, in general such a construction isintended to be disjunctive (e.g., any of these phrases would include butnot be limited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, or A, B, and C together,and may further include more than one of A, B, or C, such as A₁, A₂, andC together, A, B₁, B₂, C₁, and C₂ together, or B₁ and B₂ together). Itwill be further understood that virtually any disjunctive word or phrasepresenting two or more alternative terms, whether in the description,claims, or drawings, should be understood to contemplate thepossibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

The herein described aspects depict different components containedwithin, or connected with, different other components. It is to beunderstood that such depicted architectures are merely examples, andthat in fact many other architectures can be implemented which achievethe same functionality. In a conceptual sense, any arrangement ofcomponents to achieve the same functionality is effectively “associated”such that the desired functionality is achieved. Hence, any twocomponents herein combined to achieve a particular functionality can beseen as “associated with” each other such that the desired functionalityis achieved, irrespective of architectures or intermedial components.Likewise, any two components so associated can also be viewed as being“operably connected,” or “operably coupled,” to each other to achievethe desired functionality. Any two components capable of being soassociated can also be viewed as being “operably couplable” to eachother to achieve the desired functionality. Specific examples ofoperably couplable include but are not limited to physically mateable orphysically interacting components or wirelessly interactable orwirelessly interacting components.

With respect to the appended claims the recited operations therein maygenerally be performed in any order. Also, although various operationalflows are presented in a sequence(s), it should be understood that thevarious operations may be performed in other orders than those which areillustrated, or may be performed concurrently. Examples of suchalternate orderings may include overlapping, interleaved, interrupted,reordered, incremental, preparatory, supplemental, simultaneous,reverse, or other variant orderings, unless context dictates otherwise.Use of “Start,” “End,” “Stop,” or the like blocks in the block diagramsis not intended to indicate a limitation on the beginning or end of anyoperations or functions in the diagram. Such flowcharts or diagrams maybe incorporated into other flowcharts or diagrams where additionalfunctions are performed before or after the functions shown in thediagrams of this application. Furthermore, terms like “responsive to,”“related to,” or other past-tense adjectives are generally not intendedto exclude such variants, unless context dictates otherwise.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

The invention claimed is:
 1. An apparatus comprising: a plasmonicnanoparticle dimer including; a first plasmonic nanoparticle having afirst magnetic element at least partially covered by a firstnegative-permittivity layer comprising a first plasmonic outer surface;and a second plasmonic nanoparticle having a second magnetic element atleast partially covered by a second negative-permittivity layercomprising a second plasmonic outer surface; a separation controlstructure disposed between the first plasmonic outer surface and thesecond plasmonic outer surface and configured to maintain adielectric-filled gap between the first plasmonic outer surface and thesecond plasmonic outer surface; and the dielectric-filled gap comprisinga distinct physical layer and extending beyond the first plasmonic outersurface or the second plasmonic surface in at least one direction,wherein a magnetic attraction between the first magnetic element and thesecond magnetic element binds the first plasmonic nanoparticle and thesecond plasmonic nanoparticle together, separated by thedielectric-filled gap maintained by the separation control structure,and wherein the first plasmonic outer surface, the dielectric-filledgap, and the second plasmonic outer surface are configured tocooperatively support bonding surface plasmons.
 2. The apparatus ofclaim 1, wherein the first negative-permittivity layer includes ametallic layer.
 3. The apparatus of claim 1, wherein the secondnegative-permittivity layer includes a metallic layer.
 4. The apparatusof claim 1, wherein the first magnetic element includes a ferromagneticor paramagnetic element.
 5. The apparatus of claim 1, wherein the firstmagnetic element includes a permanent magnetic element.
 6. The apparatusof claim 1, wherein the first magnetic element includes a magnetisableelement.
 7. The apparatus of claim 1, wherein the separation controlstructure includes a non-electrically conductive separation controlstructure.
 8. The apparatus of claim 1, wherein the separation controlstructure includes a dielectric film or dielectric coating applied tothe first plasmonic nanoparticle.
 9. The apparatus of claim 1, whereinthe separation control structure includes at least one dielectricelement projecting outward from the first plasmonic outer surface. 10.The apparatus of claim 1, wherein the separation control structureincludes a dielectric spacer element coupled with the first plasmonicouter surface.
 11. The apparatus of claim 1, wherein the separationcontrol structure includes a dielectric-filled gap separating the firstplasmonic outer surface from the second plasmonic outer surface.
 12. Theapparatus of claim 1, wherein the separation control structure isconfigured to establish or maintain a selected dielectric-filled gapbetween the first plasmonic outer surface and the second plasmonic outersurface.
 13. The apparatus of claim 1, wherein the separation controlstructure is configured to establish or maintain a dielectric-filled gapbetween the first plasmonic outer surface and the second plasmonic outersurface.
 14. The apparatus of claim 1, wherein the dielectric-filled gapis less than a maximum chord length of the first plasmonic nanoparticle.15. The apparatus of claim 1, wherein the dielectric-filled gap is lessthan about 50 nm.
 16. The apparatus of claim 1, wherein thedielectric-filled gap is less than about 20 nm.
 17. The apparatus ofclaim 1, wherein the dielectric-filled gap is less than about 10 nm. 18.The apparatus of claim 1, further comprising: the plasmonic nanoparticledimer in a gas, fluid, or solid colloidal.
 19. The apparatus of claim 1,further comprising: the plasmonic nanoparticle dimer in a colloidalsuspension.
 20. The apparatus of claim 1, further comprising: theplasmonic nanoparticle dimer in a colloidal solution.
 21. The apparatusof claim 1, wherein the plasmonic nanoparticle dimer is configured tohave a selected resonant band frequency signature or profile.
 22. Theapparatus of claim 1, wherein the plasmonic nanoparticle dimer isconfigured to have a selected optical absorption spectrum.
 23. Theapparatus of claim 1, wherein the plasmonic nanoparticle dimer isconfigured to have a selected Raman scattering signature or profile. 24.The apparatus of claim 1, wherein the plasmonic nanoparticle dimerincludes a plasmonic nanoparticle trimer, and the trimer includes athird plasmonic nanoparticle having a third magnetic element at leastpartially covered by a third negative-permittivity layer comprising athird plasmonic outer surface.
 25. A system comprising: a mixture of aplurality of plasmonic nanoparticle dimers in a dispersion medium; eachplasmonic nanoparticle dimer of the plurality of plasmonic nanoparticledimers including; a first plasmonic nanoparticle having a first magneticelement at least partially covered by a first negative-permittivitylayer comprising a first plasmonic outer surface; a second plasmonicnanoparticle having a second magnetic element at least partially coveredby a second negative-permittivity layer comprising a second plasmonicouter surface; a separation control structure configured to maintain adielectric-filled gap between the first plasmonic outer surface and thesecond plasmonic outer surface; the dielectric-filled gap comprising adistinct physical layer and extending in at least one direction beyondthe first plasmonic outer surface or the second plasmonic surface; andthe dispersion medium, wherein a magnetic attraction between the firstmagnetic element and the second magnetic element binds the firstplasmonic nanoparticle and the second plasmonic nanoparticle together,separated by the dielectric-filled gap maintained by the separationcontrol structure, wherein the first plasmonic outer surface, thedielectric-filled gap, and the second plasmonic outer surface areconfigured to cooperatively support bonding surface plasmons.
 26. Thesystem of claim 25, wherein the mixture includes a colloidal.
 27. Thesystem of claim 25, wherein the dispersion medium includes a fluid. 28.The system of claim 25, wherein the dispersion medium includes a solid.29. The system of claim 25, further comprising: a capsule configured tohold the mixture.
 30. An apparatus comprising: a plasmonic nanoparticledimer including; a first plasmonic nanoparticle having a first magneticelement at least partially covered by a first negative-permittivitylayer comprising a first plasmonic outer surface; and a second plasmonicnanoparticle having a second magnetic element at least partially coveredby a second negative-permittivity layer comprising a second plasmonicouter surface; a separation control structure configured to maintain adielectric-filled gap between the first plasmonic outer surface and thesecond plasmonic outer surface; and the dielectric-filled gap comprisinga distinct physical layer and extending beyond the first plasmonic outersurface or the second plasmonic surface in at least one direction,wherein the first magnetic element and the second magnetic elementmagnetically attract each other, and bind the first plasmonicnanoparticle and the second plasmonic nanoparticle together separated bythe dielectric-filled gap, the binding configured to resist a separationof the first plasmonic nanoparticle from the second plasmonicnanoparticle during movement in a dispersion medium, and wherein thefirst plasmonic outer surface, the dielectric-filled gap, and the secondplasmonic outer surface are configured to cooperatively support bondingsurface plasmons.
 31. A system comprising: a mixture of a plurality ofplasmonic nanoparticle dimers in a dispersion medium; each plasmonicnanoparticle dimer of the plurality of plasmonic nanoparticle dimersincluding; a first plasmonic nanoparticle having a first magneticelement at least partially covered by a first negative-permittivitylayer comprising a first plasmonic outer surface; and a second plasmonicnanoparticle having a second magnetic element at least partially coveredby a second negative-permittivity layer comprising a second plasmonicouter surface; a separation control structure configured to maintain adielectric-filled gap between the first plasmonic outer surface and thesecond plasmonic outer surface; the dielectric-filled gap comprising adistinct physical layer and extending in at least one direction beyondthe first plasmonic outer surface or the second plasmonic surface; andthe dispersion medium, wherein the first magnetic element and the secondmagnetic element magnetically attract each other, and bind the firstplasmonic nanoparticle and the second plasmonic nanoparticle togetherseparated by the dielectric-filled gap, the binding configured to resista separation of the first plasmonic nanoparticle from the secondplasmonic nanoparticle during movement in the dispersion medium, andwherein the first plasmonic outer surface, the dielectric-filled gap,and the second plasmonic outer surface are configured to cooperativelysupport bonding surface plasmons.